Previously, many types of color shade guides have been in use allowing the dental practitioner to match the color of a patients tooth and communicate the color to the manufacturer, fabricating a restoration. In the past, a number of color samples have been attached to either a fixed, rotatably separate metal plate or an artificial tooth, or portion thereof, attached to a separable holder. In any event, the dentist positions the color sample on or near the tooth being restored in order to visually ascertain and classify the color of the natural tooth. In most cases, prior art has reproduced a tooth in basic shape and size, even to the extent that the entire exposed surface of the tooth has been formed and a handle member is attached to allow manipulation. Further, some devices utilize pivot connections between the specimen and the handle, allowing convenient positioning in the oral cavity.
A search of the prior art did not disclose any patents that read directly on the claims of the instant invention, however, the following U.S. patents were considered related:
______________________________________ U.S. Pat. No. Inventor Filing Date ______________________________________ 4,620,841 Farrell et al Dec. 24, 1984 4,541,801 Rodenbach et al Apr. 13, 1984 4,207,678 Jeannette Sep. 26, 1977 4,115,922 Alderman Sep. 20, 1976 3,964,167 Yerkes Oct. 24, 1974 3,378,925 Faller Jul. 14, 1965 2,805,478 Adams Jan. 20, 1955 ______________________________________
Farrell et al teach a metal blank with metal bars covered with dental glass fused onto a layer of different colored opaque material with a clear glaze on the top. The shade guide is configured as a single element with individual colors in a contiguous arcuate fan-like array allowing the guide to be held and the particular shade matched to the material tooth by the position maintained.
Rodenbach discloses a number of removable color rods for color comparison. The rods project from a frame and a stud snaps into a bore holding it in place in this frame. The rods are positioned side by side and are individually removed for use. The rod does not have the shape of the tooth, instead is rectangular, the same width as the balance of the rod.
Jeannette similarly provides a holder for guides stored side by side. The individual guides have either a specific chroma percentage or a primary shade. In use, a primary color is selected which matches most closely the patients natural teeth. A set of secondary shade guides correspond to the primary, except they contain a selected chroma percentage defined by a predetermined value ratio achieved by a color modifier allowing selection of the nearest color by comparison. The color specimens are in somewhat the shape of a tooth and have a handle on the opposite end.
Alderman teaches a shading system with both gingival and incisal shade selectors with the holder hinged in the middle. Shade buttons of the gingival selectors are concave, tapering to a thin edge and the incisal selectors are convex and relatively thicker. Each selector is removable from the hinged case.
Yerkes utilizes a disposable tooth shade guide with a tooth simulating member much the same shape as a tooth. A mounting member pivotally holds the tooth and a translucent cover alters the color by having different color variations producing a combined color. The cover may be removed and discarded after use.
Faller's approach to the problem of sanitation uses a tank filled with disinfectant in which the shade guide is immersed. A support, in the form of a lid having a center wall member with slots on each side, secure individual elements. The slot is outwardly tapered to hold the individual elements in place.
Adams pivots a set of artificial teeth of different hues in a holder allowing a desired number of teeth to be selectively positioned adjacent to the oral cavity of a patient. The non-required teeth may be moved laterally away and supported in that position while the comparison is being made.
It is very apparent that the prior art has limited its attention to guides that are maintained in sets either connected together and pivoted or individual samples capable of being selected for comparison and thereafter stored in a convenient container. Nowhere has a truly economically feasible, disposable guide been employed.